Gene losses in the common vampire bat illuminate molecular adaptations to blood feeding.

Vampire bats are the only mammals that feed exclusively on blood. To uncover genomic changes associated with this dietary adaptation, we generated a haplotype-resolved genome of the common vampire bat and screened 27 bat species for genes that were specifically lost in the vampire bat lineage. We found previously unknown gene losses that relate to reduced insulin secretion ( and ), limited glycogen stores (), and a unique gastric physiology (). Other gene losses likely reflect the biased nutrient composition ( and ) and distinct pathogen diversity of blood () and predict the complete lack of cone-based vision in these strictly nocturnal bats ( and ). Notably, loss likely helped vampire bats adapt to high dietary iron levels by enhancing iron excretion, and the loss of could have contributed to their exceptional cognitive abilities. These findings enhance our understanding of vampire bat biology and the genomic underpinnings of adaptations to blood feeding.